Editing Yard (section)

===19th-century Britain===
Following [[Royal Society]] investigations by [[John Playfair]], [[William Hyde Wollaston]] and John Warner in 1814 a committee of parliament proposed defining the standard yard based upon the length of a [[seconds pendulum]]. This idea was examined but not approved.<ref name="Dowling1872">{{cite book|author=Charles Hutton Dowling|title=A series of metric tables: in which the British standard measures and weights are compared with those of the metric system at present in use on the continent|url=https://archive.org/details/aseriesmetricta00dowlgoog|year=1872|publisher=Lockwood|pages=xii–iii}}</ref> The [[Weights and Measures Act 1824]] ([[5 Geo. 4]]. c. 74) ''An Act for ascertaining and establishing Uniformity of Weights and Measures'' stipulates that:<ref name="Britain1824">{{cite book|author=Great Britain|title=The statutes of the United Kingdom of Great Britain and Ireland (1807–1865)|url=https://archive.org/details/statutesunitedk02britgoog|year=1824|publisher=His Majesty's statute and law printers|pages=[https://archive.org/details/statutesunitedk02britgoog/page/n373 339]–354}}</ref>

{{boxquote|From and after the First Day of ''May'' One thousand eight hundred and twenty five the Straight Line or Distance between the Centres<!--sic--> of the Two Points in the Gold Studs of the Straight Brass Rod now in the Custody of the Clerk of the House of Commons whereon the Words and Figures "Standard Yard 1760" are engraved shall be and the same is hereby declared to be the original and genuine Standard of that Measure of Length or lineal Extension called a Yard; and that the same Straight Line or Distance between the Centres of the said Two Points in the said Gold Studs in the said Brass Rod the Brass being at the Temperature of Sixty two Degrees by ''Fahrenheit'''s Thermometer shall be and is hereby denominated the Imperial Standard Yard and shall be and is hereby declared to be the Unit or only Standard Measure of Extension, wherefrom or whereby all other Measures of Extension whatsoever, whether the same be lineal, superficial or solid, shall be derived, computed and ascertained; and that all Measures of Length shall be taken in Parts or Multiples, or certain Proportions of the said Standard Yard; and that One third Part of the said Standard Yard shall be a Foot, and the Twelfth Part of such Foot shall be an Inch; and that the Pole or Perch in Length shall contain Five such Yards and a Half, the Furlong Two hundred and twenty such Yards, and the Mile One thousand seven hundred and sixty such Yards.}}

In 1834, the primary Imperial yard standard was partially destroyed in a fire known as the [[Burning of Parliament]].<ref name="Report on Restoration of Standards">{{cite report
|first1=G. B. |last1=Airy
|author-link1=George Biddell Airy
|first2= F. |last2=Baily
|author-link2=Francis Baily
|first3=J. E. D. |last3=Bethune
|author-link3=John Elliot Drinkwater Bethune
|first4= J. F. W. |last4=Herschel
|author-link4=John Herschel
|first5 =J. G. S. |last5=Lefevre
|author-link5=John Shaw Lefevre
|first6 =J. W. |last6=Lubbock
|author-link6=Sir John Lubbock, 3rd Baronet
|author7 =G. Peacock
|author-link7=George Peacock
|first8 =R. |last8=Sheepshanks
|author-link8=Richard Sheepshanks
|year       = 1841
 | title       = Report of the Commissioners appointed to consider the steps to be taken for restoration of the standards of weight & measure
 | url         = https://books.google.com/books?id=4xVSAAAAcAAJ
 | publisher   = W. Clowes and Sons for Her Majesty's Stationery Office
 | location    = London
 | access-date = April 20, 2020
| quote       =We shall in the first place describe the state of the Standards recovered from the ruins of the House of Commons, as ascertained in our inspection of them made on 1st June, 1838, at the Journal Office…  No. 1. A brass bar marked “Standard [G. II. crown emblem] Yard, 1758,” which on examination was found to have its right hand stud perfect, with the point and line visible, but with its left hand stud completely melted out, a hole only remaining. The bar was somewhat bent, and discoloured in every part. No. 2. A brass bar with a projecting cock at each end, forming a bed for the trial of yard-measures; discoloured. No. 3. A brass bar marked “Standard [G. II. crown emblem] Yard, 1760,” from which the left hand stud was completely melted out, and which in other respects was in the same condition as No. 1. No. 4. A yard-bed similar to No. 2; discoloured. … It appears from this list that the bar adopted in the Act 5th Geo. IV., cap. 74, sect. 1, for the legal standard of one yard, (No. 3 of the preceding list), is so far injured, that it is impossible to ascertain from it, with the most moderate accuracy, the statutable length of one yard. … We have therefore to report that it is absolutely necessary that steps be taken for the formation and legalizing of new Standards of Length and Weight.}}</ref>{{refn|group="n"|The following references are useful for identifying the authors of the preceding reference: Ref.,<ref name="Memoir of Francis Baily">{{cite report
 |  author=J. F. W. Herschel
| author-link=John Herschel
| title       = Memoir of Francis Baily, Esq
| year       = 1845
| url         = https://books.google.com/books?id=VBxkAAAAcAAJ&q=%22members+%28Mr.+Baily+being+one%29+to+report%22&pg=PA23
 | pages=23–24
| publisher =Moyes and Barclay
| location = London
 | access-date = April 20, 2020}}</ref> Ref.,<ref name="Royal Commission Munutes 1874">{{cite report
| title       = Royal commission on scientific instruction and the advancement of science: Minutes of evidence, appendices, and analyses of evidence, Vol. II
| year       = 1874
| url         = https://books.google.com/books?id=VBxkAAAAcAAJ&q=%22members+%28Mr.+Baily+being+one%29+to+report%22&pg=PA23
 | page=184
| publisher =George Edward Eyre and William Spottiswoode Printers of the queen's most excellent majesty for Her Majesty's Stationery officer
| location = London
 | access-date = April 20, 2020}}</ref> and Ref.<ref name="Edinburgh Review Report on Restoration of Standards">{{Citation
| year  = 1843
| title  =Art. VIII.—''Report of the Commissioners appointed to consider the steps to be taken for restoration of the standards of weight and measure.'' Presented to both Houses of Parliament by Command of her Majesty, 1841.
| url  =https://books.google.com/books?id=2S84AQAAIAAJ&pg=PA228
| magazine   = [[Edinburgh Review#Edinburgh Review, 1802–1929|The Edinburgh Review]]
| volume  = 77
| issue = February 1843 … April 1843
| publisher = Ballantyne and Hughes
| location = Edinburgh
| page  = 228}}</ref>}}. In 1838, a commission{{refn|group="n"|Whose report was referenced in Ref.<ref name="Report on Restoration of Standards"/>}} was formed to reconstruct the lost standards, including the troy pound, which had also been destroyed.{{sfn|Connor|1987|p=261}} In 1845, a new yard standard was constructed based on two previously existing standards known as A1 and A2, both of which had been made for the Ordnance Survey, and R.S. 46, the yard of the [[Royal Astronomical Society]]. All three had been compared to the Imperial standard before the fire.

The new standard was made of Baily's metal No. 4 consisting of 16 parts copper, {{frac|2|1|2}} parts tin, and 1 part zinc. It was 38 inches long and 1 inch square. The [[Weights and Measures Act 1855]] granted official recognition to the new standards. Between 1845 and 1855 forty yard standards were constructed, one of which was selected as the new Imperial standard. Four others, known as 'parliamentary copies', were distributed to the Royal Mint, the Royal Society of London, the Royal Observatory at Greenwich, and the New Palace at Westminster, commonly called the Houses of Parliament.<ref name="Zupko1990">{{cite book|first=Ronald Edward |last=Zupko |author-link=Ronald Edward Zupko |title=Revolution in measurement: Western European weights and measures since the age of science |url=https://archive.org/details/bub_gb_uYCNFkRgXCoC |year=1990|publisher=American Philosophical Society|isbn=978-0-87169-186-6 |page=[https://archive.org/details/bub_gb_uYCNFkRgXCoC/page/n195 183]}}</ref> The other 35 yard standards were distributed to the cities of London, Edinburgh, and Dublin, as well as the United States and other countries (although only the first five had official status).{{sfn|Connor|1987|p=264–266}} The imperial standard received by the United States is known as "Bronze Yard No. 11"<ref>{{Cite web |url=http://museum.nist.gov/object.asp?ObjID=17 |title=NIST museum collection |access-date=January 22, 2012 |archive-date=March 3, 2016 |archive-url=https://web.archive.org/web/20160303234926/http://museum.nist.gov/object.asp?ObjID=17 |url-status=dead }}</ref>

The [[Weights and Measures Act 1878]] ([[41 & 42 Vict.]] c. 49) confirmed the status of the existing yard standard, mandated regular intercomparisons between the several yard standards, and authorized the construction of one additional Parliamentary Copy (made in 1879 and known as Parliamentary Copy VI).<ref name="Britain1878">{{cite book|author=Great Britain|title=Statutes at large|url=https://archive.org/details/statutesatlarge15unkngoog|year=1878|pages=[https://archive.org/details/statutesatlarge15unkngoog/page/n320 308]–341}}</ref>